tabdev {labdsv}R Documentation

Table Deviance

Description

Calculates the species (column-wise) and total deviance of a classified vegetation data frame

Usage

veg,clustering,nitr=1000)

Arguments

veg a vegetation (or other taxon) data frame
clustering an integer vector specifying class membership for each plot

Details

Calculates the relative abundance of taxa in classes, and then calculates the deviance associated with that taxon. Total table deviance is simple the sum of species deviances. It calculates the probability of obtaining as low a deviance as observed by permuting the species values nitr-1 times. the p-val is then calculated as (n+1)/nitr where n is the number of cases with values as low or lower than observed.

Value

a list wit components:

spcdev a dataframe with columns species, deviance, p-value
totdev total table deviance

Note

Table deviance is a useful way to test the validity of clusters derived by other means, including cutting hierarchical cluster analyses of non-hierarchical approaches. In addition, it is useful for identifying species of interest in the local flora.

Author(s)

David W. Roberts droberts@montana.edu http://ecology.msu.montana.edu/labdsv

References

http://ecology.montana.msu.edu/labdsv

See Also

duleg, duarm

Examples

    data(bryceveg) # retrieves a vegetation data frame
    clust <- sample(1:5,nrow(bryceveg),replace=TRUE)
    tabdev(bryceveg,clust)

[Package labdsv version 1.0-1 Index]